Galaxy Spins and the Cosmic Web: a Rosetta Stone for Galaxy Evolution and Weak Lensing Cosmology

Résumé fourni par la source

Galaxies spins are sculpted by the filaments of the cosmic web. Alignments between galaxy angular momentum and large-scale filaments provide both a powerful, physically-motivated tracer of galaxy assembly and a missing link between galaxy evolution and precision cosmology. Simulations and observations reveal a striking mass-dependent transition: low-mass, star-forming disks tend to spin parallel to filaments, while massive, bulge-dominated systems preferentially orient perpendicular to them, reflecting the balance between smooth accretion and merger-driven evolution. These alignments evolve with redshift, encoding how angular momentum is gained, lost, and reoriented across cosmic time. Beyond galaxy physics, spin–filament alignments are intimately connected to intrinsic alignments of galaxy shapes, one of the dominant systematics in weak-lensing surveys measuring dark energy and neutrino mass. Combining spatially-resolved kinematics with sub-Mpc reconstructions of the cosmic web offers a new, physics-driven route to model intrinsic alignments across mass, morphology, environment, and redshift. Realising this vision requires wide-field, high-density MOS and IFS surveys that both resolve the sub-Mpc cosmic web and deliver millions of galaxy spins. Such an observational leap can reveal the physics of angular momentum reorientation across cosmic time, deepening understanding of how galaxies and large-scale structures co-evolve and enabling precision weak-lensing cosmology.

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